LAPD Chief Charlie Beck said Pasasouk faces murder charges in the shootings, which occurred early Sunday outside a house that city officials said had been modified into an illegal boardinghouse. The three others face charges of aiding a felon; Alcantara faced an additional charge of robbery.

Court records show Pasasouk has an extensive criminal record and was on probation at the time of the killings. He has several convictions dating back to at least 2004 and most recently pleaded no contest to possession of methamphetamine in 2011.

Officers went to the house in the 17400 block of Devonshire Street in Northridge about 4:25 a.m. Sunday after a 911 caller reported hearing yelling and shots fired, police said. Authorities found four people — two men and two women — shot dead outside.

Three of the victims — a man and two women — were shot on a walkway outside the house, a source familiar with the case told The Times. They were wearing hooded sweat shirts and were about two feet apart. Each had at least one bullet wound to the head.

One victim was crumpled on her knees, the source said, her face buried in the palms of her hands, "almost like she was praying." The other two victims on the walkway were face-down.

The fourth victim — a man — was farther away and appeared as if he was trying to run to the backyard when he was shot. He had at least one gunshot wound, according to the source.

"It looked like a quick kill," said the source, who spoke on the condition of anonymity because the case is ongoing.

Law enforcement sources told The Times the killings appeared to stem from a dispute over personal property, including a computer. The sources, who spoke on condition of anonymity because the case was ongoing, said detectives were surprised the dispute led to multiple deaths.

Authorities tracked the suspects to Las Vegas and ultimately the Silverton Hotel and Casino, where investigators said the group checked into a room Sunday evening. The suspects were taken into custody without incident Monday afternoon.

Authorities also released the names of the victims Thursday. Los Angeles County coroner's officials identified them as Amanda Ghossein, 24, of Monterey Park; Jennifer Kim, 26, of Montebello; Robert Calabia, 34, of Los Angeles; and Teofilo Navales, 49, of Castaic.

Coroner's spokesman Ed Winter said Los Angeles police had placed a security hold on any additional information about the deaths.